There are many unstable factors in the panel production process, which causes the threshold voltages of the driving thin film transistors of each pixel in the panel to be different. In addition, due to the prolonged working time of the thin film transistor, the thin film transistor material will be aged, causing the threshold voltage of the driving thin film transistor to drift. Moreover, the degree of aging of the thin film transistor materials in the panel is different, so that the threshold voltage drift values of the driving thin film transistors in the panel are different, thereby causing the panel to display uneven color at the same pixel voltage. And the turn-on voltage will also rise, which will result in reduced panel brightness, luminous efficiency decline.